In this paper, an atmospheric pressure argon plasma jet generated by sinusoidal power input of moderate frequency (kHz range) and designed with dual-power electrodes is characterized and studied. Particularly, the effect of driving frequency in the 60-130 kHz range on the argon plasma discharge characteristics is investigated based on the electrical and spectroscopic diagnostics. It is shown that at constant applied voltage and gas flow rate, the increase of driving frequency in the range of 60-100 kHz exerts no significant influences on discharge parameters. While once the driving frequency exceeds a certain value of about 100 kHz, the discharge becomes intense abruptly and the corresponding discharge parameters increase drastically with the driving frequency. Detailed analysis about the effect of driving frequency on discharge characteristics is presented and two different dominant electron loss mechanisms, namely transport-dominated loss and diffusion-dominated loss, are proposed to account for the distinct effects of the driving frequency on argon discharge characteristics. (C) 2011 Elsevier B. V. All rights reserved.